Depth of Field

This is the first part in my guide to flower photography. This entry is about how I use depth of field inn my work (and it is by far the most technical entry, although I have tried to make it approachable).

If you always have your camera set to full auto and you’ve never really had the courage to try any of the other settings, then I would suggest trying to set you camera to shoot in aperture priority if this is possible on your camera – everything but the aperture is still automatic, but you get a lot more creative freedom when you can adjust the aperture and because of that, the depth of field.

Here’s an example of how big a difference changing the aperture can make:

The first picture her was taken with a rather open aperture of f/3, which gives a relatively shallow depth of field (The smaller the f-number, the more open the aperture is, the more shallow the depth of field get – this might sound confusing and counter-intuitive, but you get used to this rather quickly).

If you set the aperture to f/8 the depth of field will get deeper, as you can see in the next picture here, where the snowdrops in the background are less blurry.

If you set your aperture to an even higher f-number the background gets even less blurry.

In the last picture here the aperture was set to f/18.

In the example with the snowdrops I personally prefer the first picture with a very open aperture (small f-number). The shallow depth of field results in a more calm picture, because the background becomes more blurred and because of that, the snowdrops in focus become more prominent. I also think that the picture gets more perspective, because you get the sense that the blurry background (and foreground) are further away from the snowdrops – it feels more three-dimensional.

However, it can sometimes be an advantage to have deeper depth of field. For example if you are interested in getting more details from both the foreground and the background.

When it comes to flower photography, I would typically use a deeper depth of field when I get really close to the motive – otherwise large parts of the flower will be out of focus.

An example of how shallow the depth of field gets when you get really close to the motive:

The pictures of the winter aconite on the left have a very shallow depth of field (f/4). In the middle pictures a bigger part of the flower is in focus (f/8), and in the pictures on the right almost the entire flower is in focus (f/18 in the upper picture and f/20 in the lower). The background is blurry in all of the examples because the camera is so close to the flower and therefore the background is – relatively – far away from what I have focused on.

In these cases I would therefore choose the picture with the deeper depth of field (a higher f-number) so that a larger part of the flower is in focus.

Generally, when you get closer to the motive, less of it is sharp – the only exception is if the motive is entirely flat and has been captured straight on, so that everything is exactly the same distance from the camera (but that rarely happens in out three-dimensional world).

Open the aperture more if the pictures are blurred or grainy:

The more open the aperture is (i.e. smaller f-number), the more light the camera lets in and vice versa. To keep the picture from getting overexposed the camera will automatically use a faster shutter speed (and/or lower the ISO) – and with a small aperture the camera will use a slower shutter speed (and/or increase the ISO).

On sunny days there is no problem because there is plenty of light, and no matter what aperture you use the shutter speed will be quite fast (and the ISO will be quite low). But there are times when there isn’t as much light available for example on cloudy days or during sunset.

If your pictures are shaky it is a sign that the shutter speed is too slow. Maybe it is windy and the flower is moving. In this case it helps to open the aperture (lower the f-number) so that it lets in more light – this will make the camera use a faster shutter speed. This will also help if the pictures are getting too grainy because the camera has increased the ISO too much.

So my advice is to open the aperture a lot if you want sharp pictures at times when there isn’t a lot of light.

Even though you cannot adjust the aperture you can still work with depth of field:

Because the distance to the subject you are focusing on also has an effect on how much of the picture is in focus, you can control the depth of field to some degree by moving closer to or further away from the subject. If you move closer to the flower the background will get more blurry, and if you go further a way, a larger part of the flower will be sharp and so will the background.

This trick can also be used if there isn’t enough light for you to use a high f-number but you still want a deeper depth of field. In that case you can step back a little and take the picture from further away. To get the same framing you will then have to crop the picture afterwards, but if is only for use on the internet, you can crop your pictures quite a lot without any notable effects. If you need to use your picture for print this method is not advisable, as it does adversely affect the resolution.

Camera settings:

If you want to shoot in aperture priority on my Nikon camera you have to put the camera into setting “A”, and on Canon the setting is called “AV”. Adjusting the aperture is done with the middle finger on the wheel located just beneath the shutter release button.

Even if you camera is not quite that advanced, a lot of smaller cameras also let you adjust your aperture and shoot in aperture priority mode in other ways, but check your camera manual (or just google it) if you are in doubt.